Handgrip having an adjustable length

ABSTRACT

A handgrip having an adjustable length having a handle terminating in a first end and a second end and a first restraining element attached to the first end of the handle and a second restraining element engaged with the second end of the handle, the second restraining element positioned a distance D from the first restraining element. Means are provided to change the distance D between the first restraining element and the second restraining element to adjust to different hand breadths and means are also provided to secure the second restraining element to the second end of the handle. A sleeve is preferably attached to the second restraining element and a detent can be provided between the second restraining element and the second end of the handle. Indicia can also be provided on the second end of the handle to indicate the setting of the adjustment means.

This Appln claims the benefit of U.S. Provisional No. 60/042,557, filedMar. 31, 1997.

FIELD OF THE INVENTION

The invention relates to the field of handgrips for hand tools, powertools, ski poles, and other related instruments, and more particularlyto a handgrip having an adjustable length.

BACKGROUND OF THE INVENTION

Tools which a user grips for support or operation are part of mostpeople's every day recreational and work life. From ski poles to manualand power tool handgrips, all require maximum hand control for safetyand performance.

NASA anthropometric measurements show that there are substantialvariations in hand breadth within gender as well as between genders. Inassuming grip positions, the power grasp is the grip used inapplications such as holding a power drill, carrying a pipe, or graspinga ski pole where the thumb is generally in direct opposition to thefingers, and it is the maximum force that can be exerted by the hand.The oblique grasp is the grip used with tools such as wrenches,screwdrivers, and paint scrapers, and it can utilize only about 65percent of the strength of the power grip. Both grip types demanddifferent handgrip lengths consistent with hand breadth variations formaximum comfort and effectiveness. A continuous muscular stress greaterthan approximately 15% of the maximum stress of a muscle group resultsin early fatigue of that muscle group with attendant compromise of taskeffectiveness, increased musculoskeletal disorders, and accident rates.(W. Rohmert, Applied Ergonomics, Vol. 4, pages 91-95, 1973; ButterworthScientific Ltd.) From skiers gripping ski poles to workers operatingvarious types of hand and power tools, it is important for those usersto maximize control while exerting minimal muscular effort and therebyreducing fatigue.

The upper bearing surface of the hand is the thumb and first digit orradial segment of the hand and the lower bearing surface of the hand isthe outside edge or ulnar portion of the hand. When a hand grasps ahandgrip, the palmar region normally presses against the handgrip bodyto control the implement or tool. There is often insufficient purchasedepending on handgrip length and diameter, and inadequate support on theupper and lower bearing surfaces of the hand. Cradling the upper andlower bearing surfaces of the hand when gripping a handgripsubstantially increases purchase and therefore increases control andsafety while reducing the strength levels needed to successfullycomplete a task.

There have been several inventions that have focused on segmentedhandgrips that will, in effect, partially conform to a user's grip byadding spacers for grip diameter adjustment or by adding upper and/orlower projections or surfaces.

One example of a handgrip with a variable shape is U.S. Pat. No.4,645,235 which describes a multi-element ski pole handgrip, one whoseelements can be changed to offer different handgrip thicknesses. Otherexamples of designs to improve handgrip comfort and control are U.S.Pat. Nos. 4,750,760, 3,992,021, 3,879,048, and 3,436,090 which describeski pole handgrips contoured with upper and lower support surfaces.

The aforementioned patents are restricted to a particular handgriplength which corresponds to a specific hand breadth. It is critical,however, for the hand to fit snugly with the handgrip because a smallerhand relative to a handgrip will allow unwanted hand movement relativeto the handgrip, and a larger hand relative to a handgrip willcompromise grip strength and comfort because of an incorrect fit. Bothresult in decreased task effectiveness and safety. Having the ability toadjust the cradling capability of a handgrip maximizes the contactsurface area on the gripping hand and allows minimal movement of thehand relative to the handgrip. By applying this support, less effort isrequired on the part of the user to effect maximum control withsubstantially less fatigue. This functional differentiation will resultin improved performance, comfort, and safety.

There is a need for the present invention because none of theaforementioned inventions address the problem of adjusting handgrips tothe user's hand breadth.

OBJECTS OF THE INVENTION

The primary object of the invention is to provide a handgrip thatincreases grip control.

Another object of the invention is to provide a handgrip that can adjustto different hand breadths.

A further object of the invention is to provide a handgrip that is safe.

Still another object of the invention is to provide a handgrip thatminimizes fatigue.

Another object of the invention is to provide a handgrip that iscomfortable.

SUMMARY OF THE INVENTION

The present invention provides a handgrip having an adjustable lengthwhich has particular utility for use in hand tools, power tools, skipoles, and other related instruments having handgrips.

In an elementary form, the invention has a handle, which in turn has afirst end and a second end. A first restraining element is providedwhich is attached to the first end of the handle. A second restrainingelement is also provided which is engaged with the second end of thehandle and is spaced apart from the first restraining element.Adjustment means are provided to adjust the distance between the firstrestraining element and the second restraining element.

The first restraining element is a projection, tool body, hand guard, orany related protrusion from the handle that restricts either the upperor lower bearing surfaces of the hand when gripping. The secondrestraining element is also a projection or related protrusion which isadjustable along the length of the handle and also restricts either theupper or lower bearing surfaces of the hand when gripping. Takentogether, the first and second restraining elements, in effect, cradlethe user's grip by contacting both the upper and lower bearing surfacesof the hand. The adjustment of the distance between the first and secondrestraining elements is necessary to ensure sufficient contact with bothsurfaces of the hand.

It is preferred that means be provided to lockably secure the secondrestraining element to the second end of the handle.

In one preferred embodiment, the means for adjusting the distancebetween the first restraining element and the second restraining elementis accomplished by the second restraining element being frictionallyengaged with the second end of the handle.

It is further preferred that a sleeve is provided which is attached tothe second restraining element and that the sleeve is preferably taperedand preferably made of an elastically compliant material which serves tosecure the second restraining element to the second end of the handlewhen gripped.

In another preferred embodiment, the means for adjusting the distancebetween the first restraining element and the second restraining elementis accomplished by the second restraining element being threadablyengaged with the second end of the handle.

It is further preferred that a detent is provided between the secondrestraining element and the second end of the handle. It is stillfurther preferred that indicia are provided to indicate the setting ofthe adjustment means. It is further preferred that a set screw isprovided to lockably secure the second restraining element to the secondend of the handle.

In still another preferred embodiment, the second restraining element isthreadably engaged to the second end of the handle and is securedthereto by frictional means. It is further preferred that the secondrestraining element is essentially concave in configuration to the firstrestraining element.

In another preferred embodiment, the means for adjusting the distancebetween the first restraining element and the second restraining elementis accomplished by the second restraining element being slideablyengaged with the second end of the handle.

It is further preferred that a spring-loaded button is provided on thesecond end of the handle which mates with selected orifices in thesecond restraining element to lockably secure the second restrainingelement to the second end of the handle.

In still another preferred embodiment, the means for adjusting thedistance between the first restraining element and the secondrestraining element is accomplished by the second restraining elementbeing both slideably and rotatably engaged with the second end of thehandle.

It is further preferred that a passage is provided in the secondrestraining element which serves as a passage to the handle. It is stillfurther preferred that the handle is a handle to a power tool and thatthe first restraining element is preferably the body of the power tool.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross section view of one embodiment of the invention,showing the second restraining element frictionally engaged with thesecond end of the handle and showing the sleeve attached to the secondrestraining element.

FIG. 2 is an exploded view of another embodiment of the invention,showing the second restraining element threadably engaged with thesecond end of the handle and showing the detent between the secondrestraining element and the second end of the handle, the indicia on thesecond end of the handle, and the set screw on the second restrainingelement.

FIG. 3 is a partial cross section view of still another embodiment ofthe invention, showing the essentially concave second restrainingelement which is threadably engaged with the second end of the handle.

FIG. 4 is an exploded view of yet another embodiment of the invention,showing the second restraining element slideably engaged with the secondend of the handle and showing the spring-loaded button on the second endof the handle mating with selected orifices on the second restrainingelement.

FIG. 5 is an exploded view of another embodiment of the invention,showing a power tool with the invention integral thereto. The secondrestraining element is shown slideably and rotatably engaged with thesecond end of the handle.

FIG. 5A is a cross section view of a portion of the embodiment in FIG.5, showing the second restraining element slideably and rotatablyengaged with the second end of the handle and showing a passage throughthe second restraining element to the handle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the device 10 having a handle 12 which has a first end 14and a second end 16. A first restraining element 18 is attached to thefirst end 14 of the handle 12 and restricts the upper bearing surface ofthe hand when gripping the handle 12. A second restraining element 20 isfrictionally engaged with the second end 16 of the handle 12. A sleeve22, made of an elastically compliant material, is attached to the secondrestraining element 20 and encircles the second end 16 of the handle 12and a portion of the handle 12. The sleeve 22 is tapered to provide asmooth transition when gripping the handle 12. When pressure P is putaround the handle 12 as the handle 12 is gripped, the sleeve 22elastically complies with the user's hand and the handle 12, with theuser's hand providing pressure P through the sleeve 22 to the handle 12,thereby creating increased friction between the sleeve 22 and the handle12. This additional friction secures the second restraining element 20to the second end 16 of the handle 12. The second restraining element 20thereby restricts the lower bearing surface of the hand when grippingthe handle 12. When the handle 12 is not gripped, the second restrainingelement 20 can be moved relative to the second end 16 of the handle 12by overcoming the frictional resistance, thereby changing the distance Dbetween the first restraining element 18 and the second restrainingelement 20. This change in distance D allows for users with differenthand breadths to adjust the device 10 for optimal use. It is understoodthat when a user grips the handle 12, he or she also partially grips thefirst end 14 of the handle 12 and the second end 16 of the handle 12. Itis also understood that both the first restraining element 18 and thesecond restraining element 20 can fully or at least partially supportthe upper and lower bearing surfaces of the hand.

The critical element of support to the gripping hand is to maximizepurchase area between the hand and a handgrip. This effects maximumcontrol with substantially less fatigue and results in improvedperformance and safety. Cradling the upper and lower bearing surfaces ofthe hand when the hand is gripping a handgrip maximizes the surface areaof contact and allows minimal movement of the hand relative to thehandgrip. The ability to change the distance D of device 10 is importantbecause it allows the user to adjust the device 10 to his or her optimalgrip for maximum comfort, safety, and effectiveness.

Anthropometric data accumulated by NASA on men and women in the U.S.Military as well as in industry are one of the guidelines used indetermining the relative range of grip breadths.

HAND BREADTH DATA (Adapted from NASA, 1978)

    ______________________________________                                        HAND BREADTH DATA (Adapted from NASA, 1978)                                                    50th percentile ± 1 Standard                                               Deviation                                                                     Males  Females                                               ______________________________________                                        Hand Breadth (inches)                                                                            3.4 ± 0.2                                                                           3.0 ± 0.2                                      ______________________________________                                        Population Percentiles                                                                         5th       50th   95th                                        ______________________________________                                        50% Males, 50% Females                                                                         2.8       3.2    3.6                                         ______________________________________                                    

For both men and women, a hand breadth range on a handgrip thataccommodates the majority of the population (between the 5th and 95thpercentiles) is 2.8 to 3.6 inches. However, since many tools, ski poles,or other similar handgrips are used with light or heavy gloves, as wellas with bare hands, handgrip length and attendant support rangeadjustments will have to be made to optimize comfort, safety, andcontrol under varying conditions and usage.

FIG. 2 shows the device 10' with a second restraining element 20'containing female screw threads 30 which are threadably engaged to malescrew threads 32 on the second end 16' of the handle 12. When the secondrestraining element 20' is rotated about the second end 16' of thehandle 12, the distance D between the first restraining element 18 andthe second restraining element 20' (in phantom) changes. It isunderstood that the device 10' can be made having a frictional componentbetween the second restraining element 20' and the second end 16' of thehandle 12 to reduce the possibility of unwanted relative movement whichwould change the distance D between the first restraining element 18 andthe second restraining element 20' (in phantom). Since most of thepossible forces on the elements of device 10' would not cause the secondrestraining element 20' to move relative to the second end 16' of thehandle 12, only moderate friction is required to prevent the unwantedmovement and to secure the second restraining element 20' to the secondend 16' of the handle 12.

Also shown in FIG. 2 is a groove 34 in the second end 16 of the handle12, axially positioned through male screw threads 32, and a projection36 protruding from female screw threads 30. Together, the groove 34 andthe projection 36 comprise a detent when they align as the secondrestraining element 20' is rotated about the handle 12. This detent actsas a signal so the user is aware of the number of rotations performedand of the relative position of the second restraining element 20' tothe handle 12.

A set screw 38 is positioned in the second restraining element 20' sothat it can align with and seat in the groove 34 in the second end 16'of the handle 12 when the second restraining element 20' is in theappropriate position relative to the groove 34. Together, the set screw38 and the groove 34 lockably secure the second restraining element 20'relative to the second end 16' of the handle 12 to prevent any change ofdistance D.

Indicia 40 are also shown on the handle 12 and indicate the relativeposition of the second restraining element 20' and the distance Dbetween the first restraining element 18 and the second restrainingelement 20' (in phantom). The indicia 40 are helpful when there aremultiple users of a particular hand grip having differing hand breadthsor when the handgrip is used with different thickness gloves.

FIG. 3 shows the device 10' having a second restraining element 20" thatthreadably engages with the second end 16' of the handle 12. In thisfigure, the second restraining element 20" adjusts as in FIG. 2 and isan essentially concave disk. The concavity of the second restrainingelement 20" is beneficial because it provides greater surface areacontact with the lower bearing surface of the hand by cupping the handwhich results in greater control.

FIG. 4 shows the device 50, with an essentially non-round configuredhandle 52 with a first end 54 and a second end 56. The first restrainingelement 58, which is attached to the first end 54 of the handle 52, isthe bottom surface of a housing. The second restraining element 60slideably engages the second end 56 of the handle 52 and houses a seriesof orifices 62. A spring-loaded button 64, attached to the second end 56of the handle 52, aligns with the series of orifices 62 so that as thesecond restraining element 60 slides along the second end 56 of thehandle 52, the spring-loaded button 64 springably mates with one of theorifices 62, thereby lockably securing the second restraining element 60to the second end 56 of the handle 52. To change the distance D betweenthe first restraining element 58 and the second restraining element 60(in phantom), the user presses the spring-loaded button 64 to unmate thespring-loaded button 64 and the selected orifice 62, and slides thesecond restraining element 60 along the second end 56 of the handle 52until the spring-loaded button 64 mates with another selected orifice62. The series of orifices 62 also serve as indicia indicating therelative position of the second restraining element 60 and the distanceD between the first restraining element 58 and the second restrainingelement 60 (in phantom). The spring-loaded button 64 springably matedwith the selected orifice 62 visibly indicates the selected setting.

FIG. 5 shows the device 70, being the handgrip of a power tool, with anessentially round configured handle 72 with a first end 74 and a secondend 76. The first restraining element 78 which is attached to the firstend 74 of the handle 72 is the bottom surface of the motor housing ofthe power tool. A pin 80 attached to the second restraining element 82slideably and rotatably engages a configuration of connected channels 84housed in the second end 76 of the handle 72. A spring 86 is providedbetween the second restraining element 82 and the second end 76 of thehandle 72 and provides a reaction force as the second restrainingelement 82 is moved closer to the first restraining element 78. Theconnected channels 84 housed in the second end 76 of the handle 72 areconfigured to allow the second restraining element 82 to slide directlytowards the first restraining element 78, thus reducing the distancebetween the first restraining element 78 and the second restrainingelement 82, and then to allow the second restraining element 82 topartially rotate around the second end 76 of the handle 72, and then toallow the second restraining element 82 to slide nominally away from thefirst restraining element 78. The pin 80 attached to the secondrestraining element 82 stays within the connected channels 84 and allowsonly the aforementioned movements, as well as those movements in thereverse order. The spring 86 provides enough force so that when the pin80 reaches the end of a connected channel 84 after rotation, the spring86 forces the pin 80 into the end of a connected channel 84, therebylockably securing the second restraining element 82 to the second end 76of the handle 72. When the device 70 is set to a particular handbreadth, the lower bearing surface of the hand provides pressure againstthe second restraining element 82, further securing the secondrestraining element 82. It is understood that the lower bearing surfaceof the hand provides sufficient pressure on the pin 80 in the connectedchannel 84 to obviate the use of the spring 86.

FIG. 5A shows a partial cross section of device 70 from FIG. 5 withcomponents assembled. The second restraining element 82 is lockablysecured to the second end 76 of the handle 72 by the compression forceof the spring 86 between the second restraining element 82 and thesecond end 76 of the handle 72 which puts force on the pin 80 intoconnected channel 84.

Also shown in FIG. 5A is a passage 88 essentially axially positionedthrough the second restraining element 82 which allows the passage ofelectrical or pneumatic lines into the handle 72.

While the novel features of the present invention have been described interms of particular embodiments and preferred applications, it should beappreciated by one skilled in the art that substitution of materials andmodification of details obviously can be made without departing from thespirit of the invention.

What we claim is:
 1. A handgrip having an adjustable length comprising:a handle terminating in a first end and a second end; a first restraining element attached to said first end of said handle; a second restraining element slidably engaged with said second end of said handle, said second restraining element being spaced apart from said first restraining element; a spring-loaded button attached to said second end of said handle; a series of orifices on said second restraining element, said series of orifices each being positioned to selectively springably mate with said spring-loaded button to lockably secure said second restraining element with said second end of said handle, each of said orifices being configured to allow a user to press said spring-loaded button when mated therewith so as to unmate said spring-loaded button therefrom.
 2. The handgrip having an adjustable length of claim 1 wherein said second restraining element further comprises:a sleeve attached to said second restraining element, said sleeve encircling said second end of said handle, said series of orifices being provided on said sleeve.
 3. The handgrip having an adjustable length of claim 1 wherein said handle is attached to a power tool having a housing, further wherein a bottom surface of said housing serves as said first restraining element.
 4. The handgrip having an adjustable length of claim 1 wherein said second restraining element is essentially concave in configuration to said first restraining element.
 5. A handgrip having an adjustable length comprising:a handle terminating in a first end and a second end; a first restraining element attached to said first end of said handle; a second restraining element slidably and rotatably engaged with said second end of said handle, said second restraining element being spaced apart from said first restraining element; a pin attached to one of said second restraining element and said second end of said handle; and a configuration of connected channels on the other of said second restraining element and said second end of said handle,said pin movably engaging said configuration of connected channels to allow said second restraining element to move along said second end of said handle and to partially rotate around said second end of said handle.
 6. The handgrip having an adjustable length of claim 5 further comprising:a tapered sleeve attached to said second restraining element and encircling said second end of said handle,said pin being provided on said tapered sleeve and said configuration of connected channels being provided on said second end of said handle.
 7. The handgrip having an adjustable length of claim 5 further comprising:a compression spring forcibly engaging said second restraining element and said second end of said handle.
 8. The handgrip having an adjustable length of claim 5 wherein said handle is attached to a power tool having a housing, further wherein a bottom surface of said housing serves as said first restraining element.
 9. The handgrip having an adjustable length of claim 5 wherein said second restraining element is essentially concave in configuration to said first restraining element.
 10. A handgrip having an adjustable length comprising:a handle terminating in a first end and a second end; a first restraining element attached to said first end of said handle; a second restraining element movably engaged with said second end of said handle, said second restraining element being spaced apart from said first restraining element; female screw threads provided on said second restraining element; and male screw threads provided on said second end of said handle and configured to threadably engage said female screw threads so as to provide means for means for adjusting the distance between said first restraining element and said second restraining element and means for securing said second restraining element with said second end of said handle.
 11. The handgrip having an adjustable length of claim 10 wherein said means for securing said second restraining element with said second end of said handle further comprises:frictional engagement between said male screw threads on said second end of said handle and said female screw threads on said second restraining element.
 12. The handgrip having an adjustable length of claim 10 further comprising:a groove axially positioned through one of said male threads and said female threads; and a projection protruding from the other of said male threads and said female threads, said projection engaging said groove to provide a detent between said second end of said handle and said second restraining element.
 13. The handgrip having an adjustable length of claim 10 wherein said second restraining element is essentially concave in configuration to said first restraining element.
 14. The handgrip having an adjustable length of claim 10 wherein said handle is attached to a power tool having a housing, further wherein a bottom surface of said housing serves as said first restraining element. 